C# XNA 4.0 纹理在最小化时消失

Question

我是 XNA 的新手，遇到了一些问题。每当我最小化游戏时，再次打开它时屏幕会变黑。这可能是什么原因造成的，如何解决？

这是我的图像类:

 public class Image
 {
    public float Alpha;
    public string Text, FontName, Path;
    public Vector2 Position, Scale;
    public Rectangle SourceRect;
    public bool IsActive;
    public bool Logo;
    public Texture2D Texture;
    Vector2 origin;
    ContentManager content;
    RenderTarget2D renderTarget;
    SpriteFont font;
    Dictionary<string, ImageEffect> effectList;
    public string Effects;

    public FadeEffect FadeEffect;

    void SetEffect<T>(ref T effect)
    {
        if (effect == null)
            effect = (T)Activator.CreateInstance(typeof(T));
        else
        {
            (effect as ImageEffect).IsActive = true;
            var obj = this;
            (effect as ImageEffect).LoadContent(ref obj);
        }

        effectList.Add(effect.GetType().ToString().Replace("RPG.", ""), (effect as ImageEffect));
    }

    public void ActivateEffect(string effect)
    {
        if (effectList.ContainsKey(effect))
        {
            effectList[effect].IsActive = true;
            var obj = this;
            effectList[effect].LoadContent(ref obj);
        }
    }

    public void DeactivateEffect(string effect)
    {
        if (effectList.ContainsKey(effect))
        {
            effectList[effect].IsActive = false;
            effectList[effect].UnloadContent();
        }
    }

    public void StoreEffects()
    {
        Effects = String.Empty;
        foreach (var effect in effectList)
        {
            if (effect.Value.IsActive)
                Effects += effect.Key + ":";
        }

        if(Effects != String.Empty)
            Effects.Remove(Effects.Length - 1);
    }

    public void RestoreEffects()
    {
        foreach (var effect in effectList)
            DeactivateEffect(effect.Key);
        string[] split = Effects.Split(':');
        foreach (string s in split)
            ActivateEffect(s);
    }

    public Image()
    {
        Path = Text = Effects = String.Empty;
        FontName = "Fonts/FixedSys Ex";
        Position = Vector2.Zero;
        Scale = Vector2.One;
        Alpha = 1.0f;
        SourceRect = Rectangle.Empty;
        effectList = new Dictionary<string, ImageEffect>();
    }

    public void LoadContent()
    {
        content = new ContentManager(ScreenManager.Instance.Content.ServiceProvider, "Content");


        if (Path != String.Empty)
            Texture = content.Load<Texture2D>(Path);

        font = content.Load<SpriteFont>(FontName);

        Vector2 dimensions = Vector2.Zero;

        if (Texture != null)
            dimensions.X += Texture.Width;
        dimensions.X += font.MeasureString(Text).X;

        if (Texture != null)
            dimensions.Y = Math.Max(Texture.Height, font.MeasureString(Text).Y);
        else
            dimensions.Y = font.MeasureString(Text).Y;

        if (SourceRect == Rectangle.Empty)
            SourceRect = new Rectangle(0, 0, (int)dimensions.X, (int)dimensions.Y);

        renderTarget = new RenderTarget2D(ScreenManager.Instance.GraphicsDevice, (int)dimensions.X, (int)dimensions.Y);
        ScreenManager.Instance.GraphicsDevice.SetRenderTarget(renderTarget);
        ScreenManager.Instance.GraphicsDevice.Clear(Color.Transparent);
        ScreenManager.Instance.SpriteBatch.Begin();
        if (Texture != null)
            ScreenManager.Instance.SpriteBatch.Draw(Texture, Vector2.Zero, Color.White);
        ScreenManager.Instance.SpriteBatch.DrawString(font, Text, Vector2.Zero, Color.White);
        ScreenManager.Instance.SpriteBatch.End();

        Texture = renderTarget;

        ScreenManager.Instance.GraphicsDevice.SetRenderTarget(null);

        SetEffect<FadeEffect>(ref FadeEffect);

        if (Effects != string.Empty)
        {
            string[] split = Effects.Split(':');
            foreach (string item in split)
                ActivateEffect(item);
        }


    }

    public void UnloadContent()
    {
        content.Unload();
        foreach (var effect in effectList)
        {
            DeactivateEffect(effect.Key);
        }
    }

    public void Update(GameTime gameTime)
    {
        foreach (var effect in effectList)
        {
            if(effect.Value.IsActive)
                effect.Value.Update(gameTime);
        }
    }

    public void Draw(SpriteBatch spriteBatch)
    {
        origin = new Vector2(SourceRect.Width / 2, SourceRect.Height / 2);
        spriteBatch.Draw(Texture, Position + origin, SourceRect, Color.White * Alpha, 0.0f, origin, Scale, SpriteEffects.None, 0.0f);
    }
}

编辑:

我终于设法让它正常工作了!

固定代码:

public class Image
{
    public float Alpha;
    public string Text, FontName, Path;
    public Vector2 Position, Scale;
    public Rectangle SourceRect;
    public bool IsActive;
    public bool Logo;
    public Texture2D Texture;
    Vector2 origin;
    Vector2 dimensions;
    ContentManager content;
    RenderTarget2D renderTarget;
    SpriteFont font;
    Dictionary<string, ImageEffect> effectList;
    public string Effects;

    public FadeEffect FadeEffect;

    void SetEffect<T>(ref T effect)
    {
        if (effect == null)
            effect = (T)Activator.CreateInstance(typeof(T));
        else
        {
            (effect as ImageEffect).IsActive = true;
            var obj = this;
            (effect as ImageEffect).LoadContent(ref obj);
        }

        effectList.Add(effect.GetType().ToString().Replace("RPG.", ""), (effect as ImageEffect));
    }

    public void ActivateEffect(string effect)
    {
        if (effectList.ContainsKey(effect))
        {
            effectList[effect].IsActive = true;
            var obj = this;
            effectList[effect].LoadContent(ref obj);
        }
    }

    public void DeactivateEffect(string effect)
    {
        if (effectList.ContainsKey(effect))
        {
            effectList[effect].IsActive = false;
            effectList[effect].UnloadContent();
        }
    }

    public void StoreEffects()
    {
        Effects = String.Empty;
        foreach (var effect in effectList)
        {
            if (effect.Value.IsActive)
                Effects += effect.Key + ":";
        }

        if(Effects != String.Empty)
            Effects.Remove(Effects.Length - 1);
    }

    public void RestoreEffects()
    {
        foreach (var effect in effectList)
            DeactivateEffect(effect.Key);
        string[] split = Effects.Split(':');
        foreach (string s in split)
            ActivateEffect(s);
    }

    public Image()
    {
        Path = Text = Effects = String.Empty;
        FontName = "Fonts/FixedSys Ex";
        Position = Vector2.Zero;
        Scale = Vector2.One;
        Alpha = 1.0f;
        SourceRect = Rectangle.Empty;
        effectList = new Dictionary<string, ImageEffect>();
    }

    public void LoadContent()
    {
        content = new ContentManager(ScreenManager.Instance.Content.ServiceProvider, "Content");


        if (Path != String.Empty)
            Texture = content.Load<Texture2D>(Path);

        font = content.Load<SpriteFont>(FontName);

        dimensions = Vector2.Zero;

        if (Texture != null)
            dimensions.X += Texture.Width;
        dimensions.X += font.MeasureString(Text).X;

        if (Texture != null)
            dimensions.Y = Math.Max(Texture.Height, font.MeasureString(Text).Y);
        else
            dimensions.Y = font.MeasureString(Text).Y;

        if (SourceRect == Rectangle.Empty)
            SourceRect = new Rectangle(0, 0, (int)dimensions.X, (int)dimensions.Y);

        SetEffect<FadeEffect>(ref FadeEffect);

        LoadDevice();

        if (Effects != string.Empty)
        {
            string[] split = Effects.Split(':');
            foreach (string item in split)
                ActivateEffect(item);
        }

    }

    public void LoadDevice()
    {
        if (Path != String.Empty)
            Texture = content.Load<Texture2D>(Path);

        font = content.Load<SpriteFont>(FontName);

        renderTarget = new RenderTarget2D(ScreenManager.Instance.GraphicsDevice, (int)dimensions.X, (int)dimensions.Y);
        ScreenManager.Instance.GraphicsDevice.SetRenderTarget(renderTarget);
        ScreenManager.Instance.GraphicsDevice.Clear(Color.Transparent);
        ScreenManager.Instance.SpriteBatch.Begin();
        if (Texture != null)
            ScreenManager.Instance.SpriteBatch.Draw(Texture, Vector2.Zero, Color.White);
        ScreenManager.Instance.SpriteBatch.DrawString(font, Text, Vector2.Zero, Color.White);
        ScreenManager.Instance.SpriteBatch.End();

        Texture = renderTarget;

        ScreenManager.Instance.GraphicsDevice.SetRenderTarget(null);
    }

    public void UnloadContent()
    {
        content.Unload();
        foreach (var effect in effectList)
        {
            DeactivateEffect(effect.Key);
        }
    }

    public void Update(GameTime gameTime)
    {
        foreach (var effect in effectList)
        {
            if(effect.Value.IsActive)
                effect.Value.Update(gameTime);
        }
    }

    public void Draw(SpriteBatch spriteBatch)
    {
        origin = new Vector2(SourceRect.Width / 2, SourceRect.Height / 2);
        spriteBatch.Draw(Texture, Position + origin, SourceRect, Color.White * Alpha, 0.0f, origin, Scale, SpriteEffects.None, 0.0f);

        if (renderTarget.IsContentLost)
        {
            ScreenManager.Instance.SpriteBatch.End();
            LoadDevice();
            ScreenManager.Instance.SpriteBatch.Begin();
        }
    }
}

renderTarget 的内容现在在一个单独的方法中绘制，并且在 LoadContent() 中被调用一次，并且在内容被调用时在 Draw() 方法中被调用迷路了。

Answer 1

所以这里的问题是因为您正在使用 RenderTarget2D 作为纹理。

在纯 DirectX 中，只要图形设备丢失，纹理和渲染目标都会丢失其内容。这是因为视频内存中的所有内容(纹理所在的位置)都必须卸载。 XNA 在纹理方面对您进行了抽象:它在 CPU 内存中保留了纹理的副本，以便在设备重置后可以自动重新创建它。

然而，渲染目标是一件比较棘手的事情。您通常不会从预先存在的图像加载渲染目标；相反，您是直接在 GPU 本身上生成渲染目标内容。那么，如果 XNA 不能在 CPU 内存中保存其内容的副本，它如何为您重新创建渲染目标？答案是不能。当设备丢失时，您的渲染目标将丢失其内容，XNA 对此无能为力。

这就是 RenderTarget2D 类公开名为 IsContentLost 的属性的原因。这使您可以确定上述情况何时发生并做出适当的响应。您不需要创建一个新渲染目标——该对象仍然存在于内存中——但您需要再次告诉图形设备它包含什么。 p>

现在，您正在 LoadContent() 中绘制渲染目标，它只会被调用一次。您需要将负责绘制渲染目标的代码部分移到另一个方法中，并在渲染目标丢失时调用该方法。

现在，要绘制渲染目标，您需要使用 SetRenderTarget(myRenderTarget) 在图形设备上设置它。完成绘制后，您需要使用 SetRenderTarget(null) 再次取消设置，这会将后台缓冲区恢复为主要渲染目标。这一点很重要，因为渲染目标不能同时是渲染的源(即纹理)和渲染的目标。如果您尝试这样做，您将得到一个异常(exception)。

你的情况似乎很复杂，因为你正在将纹理加载到 Texture 字段中，然后将其绘制到渲染目标，然后替换 Texture带有渲染目标的字段。如果您尝试用您所拥有的执行我刚才描述的操作，您将最终尝试将渲染目标绘制到自身上——这可能是导致您所看到的异常的原因。所以不要那样做。将原始纹理存储在不同的字段中，因为稍后您将需要它来重新生成目标。